(CNN)An employee for the federal agency supervising the lease for the Trump hotel in Washington spent more than $900 for a stay there last year, according to a document reviewed by CNN -- the first publicly known movement of federal taxpayer dollars into the highly scrutinized business.

The federal employee worked for the General Services Administration, the agency which supervises the lease of the Old Post Office building to the Trump Organization.

The GSA reimbursed the employee for a majority of the charges, which was in line with the agency's policy on per diem expenses, according to a person familiar with the document. That means taxpayer dollars made their way into the hotel's coffers.

The expenses are small relative to the hotel's operation but the charge demonstrate how taxpayer money can flow into the President's businesses, stoking critics who say these payments invite corruption. Ethics hawks argue that Trump shouldn't profit from government money -- foreign or domestic and regardless of the amount.

CNN reviewed government travel expense records from the GSA, which were obtained via a Freedom of Information Act request by a government transparency group called Property of the People, a Washington-based nonprofit.

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The GSA reports show one charge last February for over $900, which accounts for the bulk of the expenses at the hotel itself. The document also shows a GSA employee spending $750 at the property's premier steakhouse BLT Prime on June 26, and while there is a financial arrangement between BLT and the hotel, the former is not owned by the Trump Organization.

GSA does not have specific guidance regarding employees use of the Trump hotel in Washington, the agency said in a response to a separate CNN FOIA request last month.

"GSA has not promulgated any guidance related to the use of properties or services of the Trump Organization properties," the agency wrote.

"GSA employees are responsible for making their own lodging and meal arrangements while on official business travel and GSA reimburses its employees at the allowable per diem rates pursuant to federal rules and regulations and GSA's Travel Policy," agency spokeswoman Pam Dixon said in an interview.

Government watchdogs and the President's opponents argue the payments to Trump's business from governments -- domestic or foreign --violate anti-corruption and self-dealing clauses in the Constitution. It says the President "shall not receive... any other Emolument from the United States" other than a salary.

Lawyers disagree over the definition of an emolument. Several lawsuits against the President, including one brought by the attorneys general of Maryland and the District of Columbia, contend that the term refers to any benefit the President receives other than his compensation.

Last month, the plaintiffs and the Justice Department lawyers defending the President appeared before a federal judge in Maryland who will decide whether the case moves forward. A judge in New York dismissed a similar lawsuit in December.

"Regardless of how much he makes on any individual transaction, the President is sending a signal that the White House is open for business," said Property of the People co-founder Ryan Shapiro, who has been a vocal critic of this administration as well as prior ones. "Due to his refusal to divest from his sprawling business empire, Donald Trump has turned the American presidency into a racket."

The relationship between GSA and the hotel has drawn concern from ethics experts. The agency manages federal buildings and land, including the historical Old Post Office building housing the Trump hotel. As a result, the GSA is tasked with protecting taxpayers' interests under a 60-year lease agreement. At the same time, the executive branch has considerable sway over the head of the GSA, which "shall perform functions subject to the direction and control of the President," according to US law. That arrangement gives the tenant effective control over the landlord.

In addition to the GSA, multiple other federal agencies have paid Trump companies for lodging or services since Trump's inauguration.

CNN previously reported that the US Secret Service paid the Mar-a-Lago Club $63,700 between roughly February and April of 2017. The payments were categorized as hotel costs on government expense forms.

In September, the Washington Post credited Property of the People for obtaining a receipt from the US Coast Guard that showed Mar-a-Lago billed the government $1,092 for a two-night stay. That charge was listed as a rack rate, which usually refers to a non-discounted price.

In 2013, Trump signed a 60-year lease with the federal government in order to transform the historic Old Post Office Building on Pennsylvania Avenue into a luxury hotel. Since opening in 2016, the Trump International Hotel offers more than 260 luxury rooms, and dining rooms for private parties, as well as a bar and spa.

Although Trump resigned from his companies before taking office, he transferred his assets into a trust that he can dissolve anytime he chooses. The arrangement allows him to benefit financially from those businesses, including the DC hotel.